The present application is directed to a transmission and, more particularly, to a multi-speed transmission for an off-highway vehicle.
Off-highway vehicles, such as, for example, wheel loaders, belted tractors, and other types of heavy machinery, are used to perform many earth-moving tasks. To effectively perform these tasks, the off-highway vehicles require a drive train that provides significant power, as well as a range of gearing that allows the vehicle to move at several different speeds. Typically, the off-highway vehicles include a multi-speed transmission that provides the necessary gearing.
An off-highway vehicle typically requires a multi-speed transmission that provides a maneuvering speed range, a working speed range, and a traveling speed range. The maneuvering speed range is generally a series of gears, or speeds, that provide for the slowest velocities of the off-highway vehicle for use in maneuvering around a job site. The working speed range is generally a series of gears, or speeds, that allow the off-highway vehicle to move at relatively slow velocities. The gears in the working speed range usually provide a relatively uniform increase in speed between gears. The traveling speed range is generally a series of gears, or speeds, that allow the off-highway vehicle to achieve a relatively high velocity, such as when traveling between job sites.
As described in U.S. Pat. No. 4,614,133, a multi-speed transmission for an off-highway vehicle typically includes a variety of gears and clutches that are disposed on a number of shafts. One of the shafts is an input shaft that is connected to an engine. Another of the shafts is an output shaft that is used to move the vehicle. The clutches are used to engage different combinations of gears that will connect the input shaft to the output shaft through a selected gear ratio. The selected gear ratio translates the rotational speed of the input shaft as provided by the engine into a desired rotational speed of the output shaft.
To generate the wide range of gear ratios required by the off-road vehicle, the multi-speed transmission typically includes a plurality of intermeshing gears and a corresponding plurality of clutches. Each of the gears may have different numbers of teeth to achieve the required gear ratios. In addition, differently designed clutches may be required to engage the different gears into the necessary gear ratios.
The manner in which the gears are engaged to provide the different gear ratios impacts the efficiency of the transmission. The efficiency of the transmission for a particular gear depends, in part, on the number of loaded gear meshes required to achieve the necessary gear ratio. Energy and efficiency are lost when the transmission requires multiple loaded gear meshes to achieve the necessary gear ratio. This drop in transmission efficiency results in a drop in the overall efficiency of the off-highway vehicle.
The number of different parts in the multi-speed transmission affects the cost of manufacturing, assembling, and repairing the multi-speed transmissions. Modifying tooling to manufacture different parts can become expensive. In addition, maintaining an adequate supply of the different parts for assembly or repair can also be costly.
The vehicle transmission of the present invention solves one or more of the problems set forth above.
One aspect of the present invention is directed to a vehicle transmission that includes an input shaft, a countershaft, and an output shaft. A plurality of clutches and gears are operatively disposed on the input shaft, countershaft, and output shaft. At least one of the clutches disposed on the input shaft is identical to at least one of the clutches disposed on the countershaft and to at least one of the clutches disposed on the output shaft.
In another aspect, the present invention is directed to a vehicle transmission that includes an input shaft, a countershaft, and an output shaft. A plurality of clutches and gears are operatively disposed on the input shaft, countershaft, and output shaft. One of the gears disposed on the input shaft is identical to one of the gears disposed on the countershaft. A second one of the gears disposed on the input shaft is identical to a second one of the gears disposed on the countershaft.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.